Dispersive optical elements disperse light by deviating the path of light passing through them by an amount that varies with wavelength. Prisms and gratings are two types of dispersive optical elements. Prisms disperse light because their geometry causes light of different wavelengths passing through them to be separated and deviated by different amounts. In diffraction gratings, light passing through the grating is diffracted into a series of orders caused by the interference of wavefronts emitted from each slit in the grating.
Dispersive optical elements are used in spectrometers. Spectrometers are used in fields including medicine, material sciences, chemistry, environmental sciences, and so on. Spectrometers use dispersive optical elements including gratings and/or prisms to facilitate analyzing the spectral composition of sampled light.
FIG. 1 illustrates an example conventional spectrometer 10. The spectrometer 10 includes a light entrance element 12 for receiving light from an external source. More generally the light entrance element 12 is referred to as an electromagnetic radiation entrance. The light is passed through a first set of collimating optics 14 to a diffraction grating 16. The diffraction grating 16 separates the light into various spectra. The separated light passes through a second set of focusing optics 18 to a detection element 20.